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Biomedical subjects

K Michi

Publications and source records attributed to K Michi.

At least 19 recordsLinked to original sources
PubMed2000

Effect of ovariectomy on bone remodeling adjacent to hydroxyapatite-coated implants in the tibia of mature rats.

PURPOSE: The purpose of this study was to examine the effects of estrogen deficiency on bone remodeling adjacent to implants in the tibia of mature rats. MATERIALS AND METHODS: Hydroxyapatite-coated implants were placed bilaterally in the proximal metaphysis of the tibia of 18 female Wistar rats (48 weeks old), and ovariectomy was performed 168 days later. As a control, sham ovariectomy was performed in a similar group of 18 rats. Six animals from each group were killed at 28, 84, and 168 days after ovariectomy. Undecalcified sections were prepared, and changes in the bone tissue around the implants were evaluated histologically. Histomorphometric measurements were made with a computer-based image analyzer to quantify the unit bone mass around each implant and the amount of implant-bone contact. RESULTS: In the cortical bone area, ovariectomy induced only a slight decrease in bone contact with the implant, compared with that in the sham-operated rats. However, both the bone volume around the implant and implant-bone contact were significantly decreased in the cancellous bone area in ovariectomized rats compared with the sham-operated rats. CONCLUSION: Thinning of the bone trabeculae holding dental implants may occur with estrogen deficiency.

Animals↗
PubMed1999

Salivary gland aplasia with cleft lip and palate: a case report and review of the literature.

We report the case of a patient with lifelong symptoms of xerostomia and a repaired bilateral cleft lip and palate. The clinical evaluation demonstrated aplasia of the major salivary glands. A review of the literature pertaining to salivary gland aplasia is presented, along with a summary of the data regarding patient gender, defect sites, hereditary background, and combined manifestations. The diagnostic methods, possible pathogenesis, and management are also discussed.

Child, Preschool↗
PubMed1999

Bone reactions to titanium screw implants in ovariectomized animals.

OBJECTIVE: The purpose of this study was to investigate the reactions of bone tissue after the placement of implants into the tibiae of osteopenic model rats. STUDY DESIGN: Commercially pure titanium screw implants were placed in the bilateral proximal tibial metaphyses 168 days after ovariectomy had been performed on 12-week-old female Wistar rats. For control purposes, implants were similarly placed in sham-ovariectomy rats. The healing process was examined histologically by means of undecalcified sections at various intervals from 7 to 168 days after implantation. Through use of an automated imaging analytic system, changes in relative bone mass and implant-bone contact were histomorphometrically evaluated. RESULTS: In the cortical bone area, only a slight difference in bone contact was noted with the implant until 28 days after implantation. However, ovariectomy significantly affected bone contact at 56 days after implantation. The rate of bone contact in the cancellous bone area and the relative bone mass around the implant were significantly lower in the test group than in the control group. CONCLUSIONS: It is considered that a decrease in bone mass causes a reduction in the contact area between implant and bone and may also cause a reduction in the supporting ability of the implant because of thinning of the surrounding bone tissue.

Animals↗
PubMed1999

Bone reactions around hydroxyapatite-coated implants in ovariectomized rats.

OBJECTIVE: The purpose of this study was to investigate bone reaction after implantation in an estrogen-deficient state by examining the changes in bone reactions within tissue surrounding implants in ovariectomized rats. STUDY DESIGN: Ninety-six 12-week-old female Wistar rats were used in the study; they were divided into 2 groups, an ovariectomized group and a sham-operated group. Hydroxyapatite-coated implants were placed in the proximal metaphyses of the tibiae 21 days after surgery. The tibiae were examined histologically by undecalcified sections at various intervals from 7 to 168 days after surgery. RESULTS: In the cortical bone area of the ovariectomized rats, the procedure did not induce any apparent changes in bone volume around the implant or in bone contact with the implant in comparison with the sham-operated rats. In contrast, both bone volume around the implant and contact of the implant with new bone were significantly decreased in the cancellous bone area in the ovariectomized rats in comparison with the sham-operated rats. CONCLUSIONS: Ovariectomy did not seriously affect bone healing after the placement of implants in cortical bone areas, but it reduced the bone contact ratio and the bone in the cancellous bone area.

Acid Phosphatase↗
PubMed1999

Amplitude and frequency spectrum of temporomandibular joint sounds from subjects with and without other signs/symptoms of temporomandibular disorders.

Temporomandibular joint (TMJ) sound is one of the most commonly recognized signs in patients with temporomandibular disorders (TMD) but is also frequently seen in asymptomatic individuals. Sound recording is therefore only meaningful if the sounds from a normal healthy joint can be differentiated from those in patients. In this study, the amplitude and power spectrum of the TMJ sounds from symptomatic patients and asymptomatic individuals were recorded and compared. The result showed that TMJ sounds from symptomatic patients had a larger amplitude than sounds from asymptomatic subjects. A significant proportion of sounds had frequencies between 2000 and 3000 Hz. It was concluded that the characteristic amplitude is worthy of further study as a sign of possible diagnostic value. Secondly, the bandwidth of the sensors used at electronic TMJ sound recording should not be less than 3000 Hz.

Acoustics↗
PubMed1998

Anatomy of microvascular anastomosis in the neck.

Structural and morphometric investigations of the vessels of the neck region were carried out on 30 cadavers (15 male and 15 female in the age range of 45 to 93 years old) to gain more knowledge of the anatomy for microvascular surgery. Our results briefly are as follows: (1) The non-common-truck type of the external carotid artery (in which each branch arises separately from the external carotid artery) was found in 76.6 percent of cases, the truncus linguofacialis type was found in 21.7 percent, and the truncus thyrolingualis type was found in 1.7 percent. (2) The smallest internal diameter (the average was 1.2 mm) was found in the superficial cervical artery. (3) The largest internal diameter (4.4 mm) was measured in the external carotid artery. (4) The longest arterial section (127.8 mm) was measured between the clavicle and mandibular margin. This vascular section or stem consisted of three parts: the supraclavicular part of the common carotid artery, the proximal section of the external carotid artery, and the first 3 cm of the facial artery. (5) In 46.6 percent of cases, the facial, lingual, and superior thyroid veins joined together and formed a thyrolinguofacialis vein. (6) The type with one external jugular vein accounted for 83.0 percent of cases, and the type with one anterior jugular vein for 67.4 percent of cases. (7) The middle thyroid vein exhibited the smallest internal diameter (average of 2.0 mm). (8) The largest internal diameter (7.9 mm) was measured in the internal jugular vein. (9) The longest vessel to receive a vascular pedicle vein was the external jugular vein, the average length of which was 99.7 mm. (10) The frequency and location of valves in the facial vein were also determined.

Aged↗
PubMed1997

Tissue reaction around miniplates used for the fixation of vascularized iliac crest bone grafts.

MATERIAL/METHOD: In six miniature pigs revascularized autologous iliac crest bone grafts were fixed with two 2.0 mm titanium miniplates to a defined defect in the angle of the mandible. Tissue reaction around the implants was examined histologically and histomorphometrically at 2, 4, and 8 weeks after surgery. RESULTS: According to the evaluation of fluorescence microradiography, the cortical and medullary circulation and healing processes of bone in the vicinity of the implanted material were not disturbed after 2 weeks. At 4 weeks after surgery osseous healing occurred at the mandibula/graft interface. The histomorphometric results for the calculated percentage of direct bone/screw contact at 2 weeks were 24% with the grafted bone and 53% with the mandible. Intensive bone formation was observed in all parts of the graft by 4 weeks. The results of direct bone/screw. contact at 4 weeks were 56% and 64% and at 8 weeks 75% and 77% for the grafted and the mandibular bone, respectively. CONCLUSION: With 2.0 mm titanium miniplates used in the animal model, stable osteosynthesis and osseous healing was evident after 8 weeks of surgery. In addition, intensive remodeling of the transplanted bone without signs of creeping substitution was noted, and the bone/screw contact of the miniplate system increased with time.

Animals↗
PubMed1997

Morphometric examination of the free scapular flap.

In this study we investigated the clinicoanatomic basis of the scapular flap by morphometric examinations of 42 cadavers. Our findings were as follows: With common-trunk type scapular vessels, the maximal lengths of arteries and veins that could be used for a flap pedicle were 93 and 91 mm. With direct-type scapular vessels, the maximal lengths were 95 and 71 mm. In common-trunk type vessels, the mean internal diameter 2 mm distal from the confluence of the scapular vessel was 2.8 mm for arteries and 3.3 mm for veins. In the direct-type vessels, the mean internal diameter 2 mm distal from the confluence of the circumflex scapular vessel was 1.8 mm for arteries and 3.3 mm for veins. The maximal superoinferior dimension of the scapular graft was 28 mm. The maximal lateral dimension of the scapular graft was 12 mm.

Adult↗
PubMed1996

Histologic and microradiologic comparison of block and particulate cancellous bone and marrow grafts in reconstructed mandibles being considered for dental implant placement.

PURPOSE: Patterns of healing were investigated in mandibles reconstructed with three different techniques to assess their readiness for implant placement. PATIENTS AND METHODS: The subjects were 10 patients who had undergone mandibular reconstruction with either nonvascularized iliac block bone grafts (group 1; 3 patients), particulate cancellous bone and marrow (PCBM) grafts (group 2; 3 patients) for mandibular discontinuity, or PCBM grafts for mandibular marginal defects (group 3; 4 patients). Six (groups 2 and 3) or 12 months (group 1) after mandibular reconstruction, bone biopsy specimens were obtained for histologic examination with a trephine bur. As controls, bone specimens were obtained from ungrafted mandibles of patients undergoing dental implant placement. Undecalcified specimens were embedded in polyester resin and examined by routine light microscopy and microradiography. RESULTS: The morphology of the specimens from group 1 was similar to that of group 2, but not to that of the control subjects. However, the morphology of specimens from group 3 was generally similar to that of control subjects. CONCLUSION: These results suggest that mandibular reconstruction with PCBM grafts allows the placement of dental implants sooner than reconstruction with block bone grafts.

Adult↗
PubMed1996

Marked enlargement of the jaws in secondary hyperparathyroidism--a case report.

A case of facial deformity and malocclusion due to secondary hyperparathyroidism is presented. Treatment consisted of parathyroidectomy, followed by recontouring of the maxilla and mandible with additional dental treatment. A 3-D reconstruction of the computed tomography (CT) scan was helpful in evaluating the facial deformities and in treatment planning.

Adult↗
PubMed1996

An anatomical study on the forearm vascular system.

The purpose of the present study was to establish the clinicoanatomical basis for the radial forearm flap. We conducted a morphometric investigation on 52 Japanese cadavers, of forearm vessels, for use in free forearm flaps. The mean inner diameter of the cephalic and median cubital veins at the interepicondylar line was 1.9 +/- 1.2 mm and 1.8 +/- 1.1 mm, respectively. Mean inner diameter of the radial artery and venae comitantes 1 cm distal to the origins of the radial and ulnar arteries was 2.3 +/- 0.5 mm and 1.6 +/- 0.5 mm, respectively. The longest segment of a superficial vein was 28.7 +/- 4.6 cm, it was measured between the basilic vein 5 cm proximal to the interepicondylar line and the cephalic vein at Lister's tubercle. The length of the radial artery was 18.1 +/- 1.7 cm. There were fewer valves in the basilic vein and cephalic vein proximal to the median cubital vein and in the brachial veins than in the distal antebrachial veins. From these results some of the clinicoanatomical considerations of forearm vessels which will form the clinicoanatomical basis of the free forearm flap should be clarified.

Adult↗
PubMed1996

The evaluation of masticatory function with low adhesive colour-developing chewing gum.

Many objective methods have been described to evaluate masticatory function. Recently, a new chewing gum system has been reported that utilizes a phloxine-sodium bicarbonate reaction and measures a chromatic coordinate as a functional indicator. A low-adhesive colour-developing chewing gum has been developed by selecting an appropriate gum base. This study examined the applicability of the system and reproducibility of results in subjects with different dental states. Tests were performed on 15 natural dentate subjects and 15 complete denture wearers after determination of germane test conditions through a pilot study. The colour was measured by a*, one of the coordinates in the L*a*b* colour system. All subjects could perform the test. The coefficient of variation ranged from 1.87% to 7.90%, averaging 5.15% in the natural dentate subjects and from 1.5% to 17.9%, averaging 9.75% in the complete denture wearers. The 95% confidence interval of a* was 28.76 +/- 1.76 in the natural dentate subjects and 10.05 +/- 2.58 in the complete denture wearers. The results indicated that this material can be useful for both complete denture wearers and subjects with a natural dentition with adequate reproducibility.

Adhesives↗
PubMed1996

A computerized method for evaluating balance of occlusal load.

In order to undertake a quantitative evaluation of balance occlusal load, the use of the Dental Prescale System was investigated. The method uses a test sheet that undergoes a colour-developing chemical reaction, for detecting contact area, and a computerized analysis system, for evaluating the balance of occlusal load. Twenty natural dentate subjects and 10 hemimaxillectomy patients participated in the study. Each subject bit a test sheet as hard as possible for 3 s. The balance of occlusal load was expressed as a percentage of the load on the side with the lesser occlusive load (%OLR). The %OLR ranged from 39.7% to 49.4% in the natural dentate subjects, and from 0% to 31.3% in the hemimaxillectomy patients at their resection site. The patients' low %OLRs were attributed to loss of sustaining structure and subjective occlusal adjustment by clinicians. Combining technical simplicity, relatively high reproducibility, and diverse analysis capability, this system is useful for quantitative evaluation of balance of occlusal load in clinical situations.

Adult↗
PubMed1996

Preliminary study of articulatory reorganisation of fricative consonants following osteotomy.

Patients who undergo osteotomy experience a radical change in the skeletal relationship between the mandible and maxilla and as yet little is known about how this affects speech articulation. This study investigated the extent to which articulatory placement for the lingual consonant /s/ changed following surgery. Using the technique of electropalatography and acoustic analysis, patients' productions of fricative sounds were recorded before and after osteotomy. Five patients were investigated, 3 with mandibular prognathism and 2 with maxillary protrusion. Results showed that there were significant changes in articulatory placement after the operation, and that these were correlated with an acoustic measure (CPF). The direction of change could be predicted on the basis of the type of operation undergone, and these changes were maintained 6 months post-operatively. The implications of the findings are discussed.

Adolescent↗
PubMed1996

Spectral properties and quantitative evaluation of hypernasality in vowels.

A new technique for evaluating hypernasality using an acoustic approach is presented. In a preliminary study using this technique, nasal resonance was assessed in 17 normal subjects and 16 subjects judged to be hypernasal. Analyses of the one-third-octave power spectra revealed an increase in power level between the first and second formant, and a reduction in the power level in second and third formant regions among utterances judged to be hypernasal. Factor analysis of the perceptual ratings revealed that the consensus perception of hypernasality accounted for 71% of the total variance. An additional 8% was accounted for by individual differences. Multiple regression analysis revealed a high correlation between the consensus perception of hypernasality and the variance in two acoustic-power levels, these being the power level between the first and second formant and the power level of the second and third formant regions.

Adolescent↗
PubMed1995

Congenital velopharyngeal incompetence in Kabuki make-up syndrome.

The Kabuki make-up syndrome is characterized by peculiar cranio-facial abnormalities, including cleft lip and palate. A case with velopharyngeal incompetence in a 7-year-old boy is reported. The significance of a possible association of this syndrome with congenital velopharyngeal incompetence is also discussed.

Abnormalities, Multiple↗